Spontaneous motility of the pig oviduct in vitro

The spontaneous motility of the pig oviductal isthmus and ampulla during the estrous cycle was recorded in vitro using an intraluminally located pressure microtransducer. A very high motility was recorded in the isthmic portion throughout the whole cycle, while the ampulla revealed an active pattern during the periovulatory period only. In proestrus the tubal pattern in both segments consisted of regular contractions of high frequency, increasing in amplitude when approaching estrus. During heat the motility changed abruptly, and was characterized by the presence of regular strong waves in the two tubal segments. This pattern might contribute to the transport of gametes to the fertilization site. After ovulation, during the time when ova are retained in the oviducts, the high preovulatory peaks disappeared. The isthmic pattern showed regular phasic contractions of high frequency and amplitude, while the ampullar motility was low. The ova are arrested at the level of the ampullar-isthmic junction (AIJ) during this period. During the short period when eggs are passing to the uterus, the ampullar motility remained low, while the isthmus showed a very active pattern with the presence of heavy contractions. This suggests the active participation of the isthmus in ovum descent. During the rest of the luteal phase, the ampulla maintained its stable low motility, while the isthmus showed an irregular although still active pattern characterized by heavy outbursts of increased activity superimposed on a consistent basal contractility.